Steven Isserlis offers his expertise to other classical musicians over a three hour event as part of the Hampstead Arts Festival

One of the more recherché pleasures of the current Hampstead Arts Festival is a masterclass to be given by cellist Steven Isserlis in Rosslyn Hill Chapel.

For Isserlis is a man of many parts, being a musicologist, a veteran festival organiser, a noted champion of music he regards as underrated, an acclaimed and sought-after soloist - and a born teacher.

His children's books about composers reflect a passionate commitment to music education: he recently republished Robert Schumann's Advice to Young Musicians, and added in some new advice of his own. Few classical musicians can match his influence.

He's now a sprightly 60, perennially sporting a wild mop of hair suggestive of a surprised hedgehog: what makes him tick? The key lies in his childhood, and in a family tree he is proud to share with Felix Mendelssohn and Karl Marx which stretches back to the sixteenth-century Polish Talmudic scholar Moses Isserles. His grandfather Julius Isserlis - a Russian-Jewish pianist-composer who studied with Tchaikovsky's pupil Taneyev, and was one of the first Soviet musicians allowed by Lenin to tour abroad (he never went back) - had a direct bearing on Steven Isserlis's development.

He has recorded some of Julius's charming, late-Romantic music, and Julius's gold medal from the Moscow conservatoire now hangs on his grandson's drawing-room wall in St John's Wood. Music-making was central to Isserlis family life. Steven's mother was a piano teacher, his father played the violin, and his elder sisters were professionals on the viola and violin respectively; taking up the cello, he completed a family ensemble which gave public performances.

At fourteen he was taken out of school and spent three years sequestered in Scotland with a teacher who inculcated the basics of his immaculately expressive style; he then studied at the Oberlin conservatory.

But Steven was a slow starter: the emptiness of his engagement diary in his twenties made him wonder if he'd ever have a career. Only when John Tavener wrote a cello concerto entitled The Protecting Veil for him in 1987, which became an overnight hit, was he finally catapulted to fame.

A public masterclass is a curious art-form, at once a group performance and an intensive moment of private coaching. So what does Isserlis hope to achieve this time? "There's a very limited amount one can achieve in one lesson," he replies. "But one can hope to give the student a fresh view, or at least a fresh voice, and a certain amount of inspiration."

What were the masterclasses which formed him? "Listening to, and occasionally taking part in, Sandor Vegh's masterclasses at IMS Prussia Cove and elsewhere. They were extremely beneficial - if at times traumatic! But I have played with, and listened to, many truly great teachers, several of them Hungarian - Ferenc and Rita Rados, and Gyorgy Kurtag."

What sort of guidance do young musicians most need? "They need to be kept to a proper set of values, of ideals, so that they work towards true musical goals, as well as being helped with the physical aspects of playing an instrument."

And what are the dangers of bad teaching?

"Bad teaching can wreck a player. It's almost as dangerous as bad medical treatment!" he says.

"Teachers have a huge responsibility - which is partly why I don't have any regular students. Teaching from week to week is an art in itself, one I have never mastered; and I have huge respect for those who do it well. I wonder whether I would even have become a cellist if I had not met my teacher - from the time I was 10 till when I was 17 - Jane Cowan. Although she is long gone, she remains a huge musical force in my life."

Applications from young soloists and ensembles to join the class are now invited, so roll up, young tyros!

Steven Isserlis gives a masterclass at Rosslyn Hill Chapel on November 21 as part of the Hampstead Arts Festival - a dozen music and literary events held between November 2-21 at various venues including Hampstead Parish Church and Burgh House.

hampsteadartsfestival.com